It is well known in the mining and shoring arts to utilize rock bolts to secure a wire mesh over the rock face of a mine roof or wall so as to stabilize the rock face and reduce the risk of injury to mine personnel by way of falling rock. Similar mesh screening means are sometimes used in excavation and shoring operations where rock or shale faces may be exposed. In both types of such operations, a suitably sized hole is drilled into the rock or shale material generally perpendicular to its face, and the rock bolt is inserted into the hole to a depth at which its threaded free end protrudes beyond the rock face by several inches. The rock bolts are retained in the drilled holes by any conventional means, and such retention means, together with the rock bolts themselves are well-known and are not part of the present invention.
After insertion of the rock bolt into a pre-drilled hole, a retention plate having a centrally positioned hole is typically placed over the protruding free end portion of the rock bolt and a conventional washer and nut are threaded onto this free end to hold fast the retention plate against the rock face and thereby stabilize the rock bolt within the rock material. Conventional forms of retention plates are readily available for this purpose, and examples thereof can be seen in U.S. Pat. Nos. 3,090,203 (Durget) and 4,740,111 (Gagnon), the teachings of which patents are hereby incorporated by reference. Once the rock bolts are installed in this manner, the wire mesh can be applied over the rock face and held thereagainst by means of secondary fastening means. Such secondary fastening means may be applied to the rock face independently of the rock bolts, or more efficiently, by attachment to the protruding free end of the rock bolts. The present invention is concerned with the provision of an improved secondary attachment means of the latter type.
The mesh screening means used is typically a wire mesh screening means, although other materials can be used. The size of the openings in the mesh screening means is larger than the diameter of the rock bolts, so that the rock bolts can pass freely therethrough. Of course, the mesh openings are sufficiently small to prevent large pieces of the rock face from breaking loose and passing through the installed mesh.